TVR engines. What do we expect?

[sideways mostly]

Dear Cyber

I had no intension of insulting you-I am sorry if you got that impression-however I have no problem speaking my mind on any occasion. If you think I have been out of line a mail to the moderator will sort me out.

I guess we are never going to agree but I do believe you are underestimating the achievement with the Speed Six. Let me explain why I think this.
You make reference to Honda’s VTEC engine-which I agree is a substantial achievement – however gaining 9000 rpm from a 2 litre inline 4 is easier to achieve than 8000 rpm from a 4 litre inline six. If you look at genuinely comparable engines-BMW’s E46 for example, you find a comparable rev limit and the same challenges of an in line six with its long crank shaft. However the TVR has a far larger swept volume per cylinder (23%) which is gained in part with the bore size and in part by a longer stroke. To reduce the mass of the piston and the associated stress in the con-rod and crankshaft at high revs the BMW engine is over square (Stroke of 91 mm, Bore of 87mm). The TVR is under square (Stroke of 92 mm and a Bore of 96 mm) and so when running at the same speed as the BMW it is moving a higher mass .The differential distance of 1 mm between the stroke dimension is not significant so it’s the mass that dominates the calculation of stress at this point not the difference in acceleration of the piston through the stroke length.In any case the TVR is the greater stroke.
In fact the TVR’s cylinder swept volume is the biggest by far of all the straight sixes that rev to these levels. The RB26DETT in the Nissan Skyline GTR is a 2.6 litre,the 3 litre Supra engine is red lined at 6800.
Long cranks are more difficult to design and balance than short cranks. The VTEC engine has a crank 33% shorter than the Speed Six which means under load it is leass affected by tortional stress.V 12's and V16's are the only engines with longer cranks than a straight six in production today. The V12 AMG modified Mercedes Benz engine in the Pagani Zonda at a swept volume of 607cc verses 666cc in the TVR.However even here there is no direct comparison as the AMG plant is pegged at a maximum of 7000 rpm and has a lower compression ration so its nothing like as stressed.

Comparing further details of the E46 with the TVR engine also has a light weight flywheel and is dry-sumped – providing better responsiveness.Although the E46 is no slouch, considerig the larger size of the Speed Six it is the more responsive.

Like the E46 the Speed Six has individual fuel air mix control for each cylinder-something that is not available on the VTEC engine.

BMW are on record as saying their ‘half an F1 engine” was a very challenging engine to develop. If the engineering might of BMW was challenged developing a high capacity (3.2 litre) high revving straight six then this puts Mr Melling and TVR’s achievement into context.


Returning to the comparison with the VTEC, the VTEC system itself as you well know is a means of achieving better breathing and combustion at higher revs so boosting power. It’s a very clever system giving the engine two modes-an every day low lift mode for normal driving and a high lift condition for the higher rev range. This also has the effect of reducing the stress on the VTEC in everyday driving. BMW have adopted a similar strategy with the new M5 engine which opperates at 400 bhp for normal driving,you have to press a button to get the full 500. The TVR engine doesn’t bother with the low lift mode or stepping down power for everyday driving so again the stresses on a day to day drive are higher than in a VTEC and the BMW V10.

These are some of the reasons I don't think the VTEC is comparable with the Speed Six


You seem to have a dim view of the TVR approach to productionising the Speed Six.I think that the production development of the Speed Six has not been fully reported yet.
It is possible that for devious reasons TVR decided to change the engine it was going to launch to avoid a commercial obligation. Its also possible that TVR decided the design as delivered was too expensive to manufacture for the target price and set about a simplification process that reduced complexity of components and build. Don’t forget TVR are sticking to their claim that the engine as delivered did not last more than 15 minutes on test .I am not aware of any challenge to this claim. If that had been their experience and they needed to engineer the prototype to a production version that they could afford to build we should not be surprised that there were changes to the original.

Another point that you might want to consider. The changes proposed to the Speed Six engine by the independents do not correct the position of the cam in relation to the valve but the geometry is returned to an acceptable state . The engine designer supported the change. I can’t comment on the degree of change achieved but I am happy to accept the designer’s word that the mod will work. If this is the case is it not possible that TVR have achieved a similar level of fix with the modifications they have made.I listed these for you before and as you may recall these included mods to oil flow and cooling as well as the valve bearing, valve and finger follower design and material spec.

I am sure in time the full story will be learnt.

Another aspect that needs to be considerred is the warranty.TVR now offer a 36k warranty. This can be extended to a limit of 8 years after an inspection and an annual payment. Contrast this with Ferrari who limit their warranty system to 56k miles and arguably TVR are offering more peace of mind than Ferrari. Look at this months report on Harry Metcalfes Ferrari in Car magazine ( issue 087) where the transmission failed . Without the additional warrant bought for the car the bill for replacing the transmission would have been £10k on top of an annual running cost of circa £12k.This makes the potential of a £5k rebuild if you don't have a warranty look allmost reasonable. Maybe Ferraris fragility is understated. The car had done 36k which I find ironic.

On your advice I looked at Spoon with interest-but don’t agree they are comparable in any way. Spoon is present in Japan and the UK and supplies the USA market as well so its not a tiny company in any sense. They formed in Japan in 1988 to supply components for Honda engines. Spoon has developed great race engines based on Honda designs and look like a great company but the design and development of tuning parts for a major manufacturers existing engine does not equate in my mind with the development of an entirely new engine from the ground up.

Finally, and I apologise for the length of my reply-CAD is useless without good engineering development. CAD is a starting point. My experience is the design of 96 cavity high-speed injection moulds and such like-CAD never delivers a ready to go solution-the real world environment always throws up conditions that the software was not able to model. This view is based on 26 years experience.

So that’s why I disagree with you-but no hard feelings Cyber!



>> Edited by sideways mostly on Thursday 15th December 23:06

>> Edited by sideways mostly on Friday 16th December 10:19

[TheArb]

DJC said:

. Me, Im rather happy to be in a powerful, light rwd sports cars and encountered no aquaplaning issues, no lousy foul weather handling issues and no foul weather traction issues. As the driver and owner of the car Im rather happy about that and considering the number of enquiries that keep popping up about the car and its ability to deal with all of the above, Id say it was pretty relevent. So, unfortunately whether you or Cyber want to try and have a go about the car, either the engine, the handling, the build quality, touring ability or just general livabiliy, so far we have an answer for you. I look forward to your next pram moment. Enjoy your Speed Six.

oooh yippee you. Can't find any posts referring to foul weather handling problems, foul weather traction problems, aquaplaning problems. Maybe you could direct me.

>> Edited by TheArb on Sunday 18th December 00:51

[TheArb]

DJC said:

5000 miles in a little under 4 months so far. To and from work. Long journeys all the country, upto Scotland, Staffs to see her family and home to Blackpool for me. So a pretty wide variety of driving. Will see how it goes.

5000 miles in the first 4 months doesn't equate to 30,000 miles in 2 years. The extrapolation isn't valid. You should know that! Keep up at the back. Take 2 seats backward. Oh you're at the back already? May as well stay there then.

[justinp1]

Ribol said:

...The only reason TVR have got away with this fiasco for as long as they have is by trading on the goodwill of their loyal customers. It is now payback time.

I think that is sadly very true. If I bought a Daewoo fridge, and because of a design flaw kept breaking down, and after 18 months of ownership (but only 6 months after it was last repaired) I had to pay for huge repair work, the last thing I would do is go back and buy another Daewoo fridge to replace it.

Why on earth would I trust Daewoo again with my money when they are not publicly explaining or attempting any goodwill toward the owners of the flawed fridges? There has been no announcement, although I am hearing 'rumours' of better build quality and parts, I am also hearing brand new fridges failing and needing the same major work done as my old one.

Put this way the situation looks quite obvious. I should either spend a bit more and get a really classy Smeg fridge (Ferrari?) or get another fridge which didnt have quite the individuality of the Daewoo (TVR?) and put my money in a Whirlpool or something similar (Porche/Merc/BMW).

Of course, I would love the Daewoo but the bloody thing never worked when I wanted it to and let me down when I needed it and ended up being more aggravation than what it was worth. Sadly 50% of this aggravation came from the company. When I needed the basic parts which orten failed (clutch anyone?) they didnt have them in stock so I was left without, and when I needed the major work done I got a two fingered salute when a mentioned that perhaps as a loyal customer that the company may with to rectify the flaws with leaving me with a huge bill.

My point is, if you would put the Speed six scenario in any other industry it is laughable. The fact that it is laughable in most other industries as people dont want to love their fridges or TVs in the way they love their sports cars. That is the reason that the sh1t hasnt hit the fan until a critical stage until now.

I said this a year ago, and will say it now, I have no doubt that what TVR would have lost in offering goodwill rebuilds back in 2001-2 (and doing the work quickly) will be small in comparison to the damage caused by the jumping ship of otherwise loyal customers and bad press and public opinion affecting potential new TVR buyers.

>> Edited by justinp1 on Saturday 17th December 21:39

[BossCerbera]

Ribol said:

It is now payback time.

[DJC]

TheArb said:

DJC said: 5000 miles in a little under 4 months so far. To and from work. Long journeys all the country, upto Scotland, Staffs to see her family and home to Blackpool for me. So a pretty wide variety of driving. Will see how it goes. 5000 miles in the first 4 months doesn't equate to 30,000 miles in 2 years. The extrapolation isn't valid. You should know that! Keep up at the back. Take 2 seats backward. Oh you're at the back already? May as well stay there then.

Dude...what the hell are you talking about? Id try and debate what you are quoting above by I havent a clue what the context is as you've snipped it all away.

So, erm, yeah, whatever, good luck and enjoy your Speed Six.

[sideways mostly]

Gazboy said:

Here to ask questions, and comment little as I'm way out of depth: sideways mostly said: I guess we are never going to agree but I do believe you are underestimating the achievement with the Speed Six. Let me explain why I think this. You make reference to Honda’s VTEC engine-which I agree is a substantial achievement – however gaining 9000 rpm from a 2 litre inline 4 is easier to achieve than 8000 rpm from a 4 litre inline six. Would it not be fairer to compare the 3.0 & 3.2 V6 NSX engines (inc the Type R)- does the far shorter crank render the comparison pointless? No idea what the swept volume of the NSX engine is btw. sideways mostly said: In fact the TVR’s cylinder swept volume is the biggest by far of all the straight sixes that rev to these levels. The RB26DETT in the Nissan Skyline GTR is a 2.6 litre,the 3 litre Supra engine is red lined at 6800. Iirc (I'm almost 99% positive on this) the limiting factor for the Supras revs are related to the turbos getting inneficient (sp?) at these engine speeds, peak power is at around 6.6k, so no real advantage to reving higher. The egt's are just far to high to rev further up. With different turbos and fuel maps the car can and will rev higher (TurboT's single runs up to 7.2k) sideways mostly said: Comparing further details of the E46 with the TVR engine also has a light weight flywheel and is dry-sumped – providing better responsiveness.Although the E46 is no slouch, considerig the larger size of the Speed Six it is the more responsive. Like the E46 the Speed Six has individual fuel air mix control for each cylinder-something that is not available on the VTEC engine. Does the NSX have this? sideways mostly said: BMW are on record as saying their ‘half an F1 engine” was a very challenging engine to develop. If the engineering might of BMW was challenged developing a high capacity (3.2 litre) high revving straight six then this puts Mr Melling and TVR’s achievement into context. I daren't say anything 'cos I'll get killed but, while a stratospheric acheivment, did they aim to high for such a company without the resources of the bigger manufactorers? : flame suit on: sideways mostly said: Returning to the comparison with the VTEC, the VTEC system itself as you well know is a means of achieving better breathing and combustion at higher revs so boosting power. It’s a very clever system giving the engine two modes-an every day low lift mode for normal driving and a high lift condition for the higher rev range. This also has the effect of reducing the stress on the VTEC in everyday driving. BMW have adopted a similar strategy with the new M5 engine which opperates at 400 bhp for normal driving,you have to press a button to get the full 500. The TVR engine doesn’t bother with the low lift mode or stepping down power for everyday driving so again the stresses on a day to day drive are higher than in a VTEC and the BMW V10. Gonna show ignorance here: Wouldn't high stress only be present when pressing on? It wouldn't be stressed at 1500rpm when trickling through town, or in a jam? Would it? Please don't kill me >> Edited by Gazboy on Tuesday 20th December 15:42

Hi Gaz

No worries mate-decent enough questions fairly put.

The NSX crank length is certainly more comparable to the speed six but the comparrison was initiated by cyber not me.I'll see if Ican dig out the swept volme of the NSX.

The Supra is a great car-a mate of mine had one and it was a real monster. You are correct the engine doesn't rev any higher because of the FI installation- tuners have acheived more ( much more!) but I was trying to compare manufacurers acheived performance. if you compare tuners and racers there are some very interesting TVR's out there with substantial hikes in the factory performance.

OK LADS POINT THE BARRELS HIS WAY

Gaz-don't look at the barrels OK,they are all on a training session.Probably best if you close your eyes... just in case

You may be right TVR may have aimed to high-thats why I love them so much.They tear up the rule book everytime and 90% of the time get away with it.
The reason for the passion is just this disparity-taking on the like of BMW,Mercedes,honda,Toyota,Nissan and getting away with it ( My view based on my experience-my T350 engine is fine, just like loads of other people's) is bloody wonderful in my book.

Some people have had real grief and I feel for them greatly.One day I may join them-but that shouldn't detract from the acheivement which is why I was going to great lengths to remind some people who may not know some of the detail.

OK CHAPS,FINGERS ON THE TRIGGERS...

Cheers
Steve



>> Edited by sideways mostly on Tuesday 20th December 18:40

[Ribol]

Gazboy said:

Would it not be fairer to compare the 3.0 & 3.2 V6 NSX engines (inc the Type R)- does the far shorter crank render the comparison pointless? No idea what the swept volume of the NSX engine is btw.

Am I missing something here

[sideways mostly]

No your not-being able to divide by six is helpful as its the swept volume of each cylinder I was looking at.

>> Edited by sideways mostly on Wednesday 21st December 07:58

[Ribol]

sideways mostly said:

its the swept volume of each cylinder I was looking at.

Just out of interest what would that tell you then?

[m12_nathan]

sideways mostly said:

I guess we are never going to agree but I do believe you are underestimating the achievement with the Speed Six. Let me explain why I think this. You make reference to Honda’s VTEC engine-which I agree is a substantial achievement – however gaining 9000 rpm from a 2 litre inline 4 is easier to achieve than 8000 rpm from a 4 litre inline six. If you look at genuinely comparable engines-BMW’s E46 for example, you find a comparable rev limit and the same challenges of an in line six with its long crank shaft. However the TVR has a far larger swept volume per cylinder (23%) which is gained in part with the bore size and in part by a longer stroke. To reduce the mass of the piston and the associated stress in the con-rod and crankshaft at high revs the BMW engine is over square (Stroke of 91 mm, Bore of 87mm). The TVR is under square (Stroke of 92 mm and a Bore of 96 mm) and so when running at the same speed as the BMW it is moving a higher mass .The differential distance of 1 mm between the stroke dimension is not significant so it’s the mass that dominates the calculation of stress at this point not the difference in acceleration of the piston through the stroke length.In any case the TVR is the greater stroke. In fact the TVR’s cylinder swept volume is the biggest by far of all the straight sixes that rev to these levels. The RB26DETT in the Nissan Skyline GTR is a 2.6 litre,the 3 litre Supra engine is red lined at 6800. Long cranks are more difficult to design and balance than short cranks. The VTEC engine has a crank 33% shorter than the Speed Six which means under load it is leass affected by tortional stress.V 12's and V16's are the only engines with longer cranks than a straight six in production today. The V12 AMG modified Mercedes Benz engine in the Pagani Zonda at a swept volume of 607cc verses 666cc in the TVR.However even here there is no direct comparison as the AMG plant is pegged at a maximum of 7000 rpm and has a lower compression ration so its nothing like as stressed.

You can stroke an S54 engine to 3.4 and get 400bhp, 440 if you go for race spec cams (obviously lumpy low doen then though). From what you are saying TVR made a bad choice to begin with. if the same power outputs are available from smaller capacities why would you go for a long throw crank and make your engine much harder to make? The csl makes 360bhp from a 3.2 I6 with 15k service intervals and vanos to provide smooth running low down and torque in the mid range, if TVR could make a 3.4 with 400 bhp then choosing a larger capacity with the engineering difficulties that that compromises and making less bhp per litre doesn't make sense?

sideways mostly said:

BMW are on record as saying their ‘half an F1 engine” was a very challenging engine to develop. If the engineering might of BMW was challenged developing a high capacity (3.2 litre) high revving straight six then this puts Mr Melling and TVR’s achievement into context.

I thought the F1 engine was actually based loosly on the 650csi engine which was 2 2.5 I6 engines together?

sideways mostly said:

Returning to the comparison with the VTEC, the VTEC system itself as you well know is a means of achieving better breathing and combustion at higher revs so boosting power. It’s a very clever system giving the engine two modes-an every day low lift mode for normal driving and a high lift condition for the higher rev range. This also has the effect of reducing the stress on the VTEC in everyday driving. BMW have adopted a similar strategy with the new M5 engine which opperates at 400 bhp for normal driving,you have to press a button to get the full 500. The TVR engine doesn’t bother with the low lift mode or stepping down power for everyday driving so again the stresses on a day to day drive are higher than in a VTEC and the BMW V10.

I don't understand this, the power created at the crank is related to how much throttle is used, not if there is a mechanism to alter cam profiles to provide a spread of torque (vtec or vanos). If anything at low revs an engine without these technologies will be far less efficient than one with them so will be less stressed as less torque is produced? Take 2 s54 engines one with vanos and one without, the one with vanos will alter cam timing to provide more torque in the midrange, more torque = more stress on the rods etc? The one without will cough and splutter and generally be a bit of a pig through the mid range rather than producing good numbers. VTEC and vanos simply allow the engineers to use a more lairy cam than they could get away with in a normal engine which is how they manage to achieve their power at high rpm. The p500 button on the M5 is a beats me though

PS. I applaud them for giving it a go but maintain that they'd have been better of either not revving so high or going for a smaller capacity and getting the power from revs. A 4L I6 is quite an ambitious first engine!

[sideways mostly]

Hi m12 nathan - sorry for the delay in replying-a holiday got in the way.I hope you had a good time yourself.
My thought for what they are worth below.

"You can stroke an S54 engine to 3.4 and get 400bhp, 440 if you go for race spec cams (obviously lumpy low doen then though). From what you are saying TVR made a bad choice to begin with. if the same power outputs are available from smaller capacities why would you go for a long throw crank and make your engine much harder to make? The csl makes 360bhp from a 3.2 I6 with 15k service intervals and vanos to provide smooth running low down and torque in the mid range, if TVR could make a 3.4 with 400 bhp then choosing a larger capacity with the engineering difficulties that that compromises and making less bhp per litre doesn't make sense?"

The danger of comparing one marques engines with another is that you can appear to criticizing someone else’s P&J-its not my intension at all, in fact I was responding to another comparison made earlier. I think BMW engines –especially VANOS and double VANOS are technically sweet solutions.That BMW have an extended service interval is great-but then it’s a very well resourced company so it can afford the testing that makes it possible. All I am asking for is that people should recognise the achievements inherent in the S6. That makes me as popular as the Pope in a brothel in some quarters but who gives a duck.Answering your specific points the BMW engines are more over-square than the TVR-so if that’s a bum move BMW have made the bigger error. In reality neither they nor TVR have made a mistake. That’s my view anyway.To answer your question directly on tuning and capacity the 3.6 version of the S6 has also been tuned to produce higher outputs - it’s the red rose option.




"I thought the F1 engine was actually based loosly on the 650csi engine which was 2 2.5 I6 engines together?"


Maybe it is –however if you look into it a little further what Gerhard Richter, Director of Development at BMW M said in an interview in April 27, 2000, was “the physical loads acting on our new M3 power unit are quite comparable to the loads you will measure in a Formula 1 engine, even though the level is somewhat different. One factor you will find in both cases, however, is the significant demand made of special materials, since the specific loads we have here are roughly the same as in Formula 1. The big difference, of course, is that a Formula 1 racing car only has to last one race, whereas a BMW M engine must last for the entire lifecycle of the car. “

And he went on to comment in the same interview that

” there is of course a fundamental exchange of experience and know-how, even though the two projects - Formula 1 and the new M3 - are entirely different in character.”

Which is hardly a surprise as the detailed engineering design, exotic materials and engineering complexity and tolerances used in F1 are far to expensive for a road car.



"I don't understand this, the power created at the crank is related to how much throttle is used, not if there is a mechanism to alter cam profiles to provide a spread of torque (vtec or vanos). If anything at low revs an engine without these technologies will be far less efficient than one with them so will be less stressed as less torque is produced? Take 2 s54 engines one with vanos and one without, the one with vanos will alter cam timing to provide more torque in the midrange, more torque = more stress on the rods etc? The one without will cough and splutter and generally be a bit of a pig through the mid range rather than producing good numbers. VTEC and vanos simply allow the engineers to use a more lairy cam than they could get away with in a normal engine which is how they manage to achieve their power at high rpm. The p500 button on the M5 is a beats me though "

My understanding is that VTEC and VANOS are quite different in operation. VTEC introduces a ‘wilder’ cam by means of a hydraulically operated pin –in effect the VTEC has two cams in one. VANOS operates by changing the degree of advance or retardation on the camshaft in relation to the crank, double VANOS achieves this for both inlet valve and exhaust valve so there in no increase in forces. Like I said its technically sweet-usually story-the innovator has the idea first (VTEC) and the follow on delivers the better application (VANOS).In either case both engines are biased towards ‘normal’ engine performance, very good engine performance, until the systems start to function-generally above 3000 rpm although the double VANOS system is continually variable which is again very sweet.The speed six remains in race mode all the way through the range.



PS. I applaud them for giving it a go but maintain that they'd have been better of either not revving so high or going for a smaller capacity and getting the power from revs. A 4L I6 is quite an ambitious first engine!


I understand where you are coming from entirely.I agree its ambitious-that’s why I like them.

[sideways mostly]

[redacted]

[thearb]

sideways mostly said:

No Car No opinion worth listening to No hope for you is there

ahh yes, the twilight zone of the poster who can't differentiate between fact and opinion. There is a lot of it around (apparently). In order:

1. "No car" yep, got one of those, hang on, two actually. Had a succession of TVRs unbroken from 1992, more than 130k miles behind the wheel. Doesn't qualify me for anything, let alone boring everybody senseless droning on about it in some kind of vain, self-publicising way like some, and I don't have it listed because I don't feel obliged to (or am I obliged to? did I miss something perhaps in the board rules), I'm not sure anyone else would find it of particular interest. Just another current model TVR, nothing special.

2. "No opinion worth listening to". I'd hate to rely on any other extrapolations you come up with, but you you're entitled to an opinion (gettit), but that doesn't make it a fact.

Sideways mostly, sometimes, rarely, whatever, who cares, "you're a 'king idiot!"

There's an opinion but it's not necessarily a fact, that may or may not be shared by others.

[thearb]

3. "No hope for you is there". Not terribly profound and an opinion not based on much substance. But if you'd like to put up your criteria, I'll try and fill in some gaps. Here's a few ideas for starters: annual earnings perhaps, no? too material? charitable donations, contributing member to the local community, respected public citizen, JP, well-read, well- travelled (well-hung even?), athlete, trusted authority.......

Put your credentials up and I'm sure my somewhat modest ones will pale into insignificance.

regards

Arb

[sideways mostly]

If you filled in your profile maybe I would know better???
Absolutely happy to be considered an idiot for defending TVR.
Happy to have a pissing competition but lets do it by email to keep this forum clean-let me know your email and I am happy to oblige.

As you are an owner and a user I am more than happy to remove my earlier post.



>> Edited by sideways mostly on Saturday 7th January 11:58